Saturday, September 15, 2018

ISCD Updates FAQ Responses – 09-14-18

Yesterday the DHS Infrastructure Security Compliance Division (ISCD) updated responses to two Frequently Asked Questions (FAQ) on the Chemical Facility Anti-Terrorism Standards (CFATS) Knowledge Center web page. Both questions deal with calculating screening threshold quantities for mixtures of flammables (one is specifically for propane).

The two revised FAQs are:

Flammable Mixtures

The response for FAQ #1373 was completely re-written with a completely different process from the original description.

The original response said essentially that when COI were in a mixture at more than 1% the entire weight of the COI was reported as the COI with the highest concentration; the facility did not report the weight of the other COI in that mixture. The exception to that was propane; if propane was in the mixture at less than 87.5% the next greatest COI in that mixture was reported, not the propane.

The new response also requires the checking of the NFPA flammability rating of the mixture. If the NFPA rating is 4 then the rule described above applies. If the NFPA rating is 1, 2 or 3 (and not a fuel), then only the actual weight of each COI in the mixture (present at 1% or more) would be reported.

Interestingly, no mention is made of propane in the new FAQ response.

Propane Mixtures

A relatively minor modification was made to the response to FAQ #1566. The second paragraph was expanded to provide more of the information from the FAQ response above for mixtures that contain less than 87.5% propane. It addresses the case where the NFPA rating of the propane containing mixture is 4. This response does not address the situation where the NFPA rating is 1, 2, or 3.

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